Critical care

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Lunnasea
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257437
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Critical care
Updated:
2014-01-19 20:43:15
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Assessment Cardiac Output SWAN
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Assessment of cardiac output
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  1. Heart Pressures
    Atrial systole
    • During atrial systole, pressure in the two atria exceeds the resistance of the ventricles.
    • This forces the tricuspid and mitral valve to open
    • Atrial ejection occurs
    • atrial kick 20-30% of cardiac output
    • Blood flows from higher to lower pressure
  2. Ventricular systole:
    • During ventricular systole, pressure in the two ventricles  exceeds the resistance of the outflow vessles.
    • Tricuspid and mital valves close
    • Pulmotic and aortic valves open
    • Ventricular ejection occurs
  3. What is Preload?
    • The volume of blood filling the ventricles at the end of diastole(just before systole occurs)
    • RV=CVP(central venous pressure)
    • LV=Pulmonary artery end diastolic pressure
    • PCWP (Capillary wedge pressure
    • These are all filling pressures
  4. Assessment of right heart preload
    • Increased R heart preload =
    • -JVD
    • Ascities
    • Hepatic engorgement
    • peripheral edema

    • Decreased R heart pressure
    • Poor skin tugor
    • Dry mucus membranes
    • Orthostatic hypotension
    • Flat jugular veins
  5. Assessment of Left sided preload
    • Increased L heart pressure
    • Dyspnea
    • cough
    • third and fourth heart sound
  6. Starlings Law
    • The force of a contraction of cardiac muscle is dependent on the stretch of cardiac muscle fibers
    • Larger the stretch....larger the contraction=good co
    • Preload is the mechanism that stretches ventricular fibers
    • The force of ventricular contraction is dependent on preload
  7. Factors affecting preload
    • Blood volume
    • -hypovolemia (dehydration)
    • -hypervolemia (fluid overload)
    • Atrial contracion
    • -Atrial kick 25-35%
    • -loss of atrial kick d/t afib
    • Venous return to heart=how much blood returns to the heart
    • -Physical factors=stenosis
    • -medication factors
    • Cardiac muscle fibers
    • -Heart failure
  8. What is Afterload?
    • Resistance to ejection of blood from ventricles
    • The pressure the ventricle must generate to overcome resistance to ejection(systole)
    • The amount of energy the LV has to generate to push the blood through the body
  9. Afterload
    • Increasing afterload increase the workload of the heart therefore increasing the O2 demand of the heart.
    • Afterload measured by systemic vascular resistance (SVR)
    • dialted blood vessels = decreased SVR
    • Constricted blood vessels = increase SVR
    • Normal SVR is 800-1200
  10. What is contractility?
    • Ability of the cardiac muscles fibers to shorten in length
    • Increased muscle fibers shortning = increased contractility= increased squeezed
    • Inotrophy agents can affect contractility
    • positive increases-ex: digoxin
    • negative decreases ex: beta blockers, calcium channel blockers
  11. Diagnostic testing: Labs
    • Creatine Phosphokinase CPK onset 4-12 hrs post damage
    • Troponin- found in cardiac muscle - onset 3-4 hrs post damage
    • B-type natriuretic peptide (BNP)
    • Hormone released from ventricles  when there is an increase in preload. Normal is 100
  12. The Pulmonary artery catheter (Swan Ganz)
    • Most invasive of critical care monitoring
    • Known as the swan-ganz or right heart catheter
    • Simutaneously assesses seveal hemodynamic parameters
    • Pumonary artery systole and diastolic pressures
    • pulmonary artery occulsion
    • cardiac output
    • central venous pressure
  13. Swan
    • RA=right atrium =cvp 2-6
    • RV=right ventricle systolic= squeeze 20-30
    • and diastolic = relaxed 2-8
    • PA=pulmonary artery
    • systole 20-30
    • diastolic 8-15
  14. CVP
    • Measures filing pressures of the right heart
    • Measures the fluid status
    • Normal CVP (RA) =2-6
    • Low cvp = hypovolemia, dehydration and when bleeding occurs, vasodilation and diuresis
    • High CVP= fluid overload, occurs in CHF and accure MI, also in renal failure
  15. PA pressures
    • Measures systole and diastole pressures of the pulmonary artery
    • reflects the state of RV and lung
    • systole = 20-30 and diastole = 8-15
    • Low pa = hypovolemia
    • High pa = Fluid overload/CHF
    • mitral stenosis
    • lung disease COPD
    • Pulmonary embolis
    • Idopathic pulmonary heypertension
  16. Pulmonary artery Wedge Pressure
    • Wedge pressure reflects blood pressure in the LV at the end of diastole
    • Wedge measures of the Left vetricular preload (left filling Pressure)
    • Low wedge = hypovolemia
    • High wedge=fluid overload, MI, cardiogenic shock, CHF
    • Normal wedge = 4-12 for the entire left side
  17. What is cardiac output?
    • The amount of blood ejected by the heart per minute
    • Normal CO=4-8 l/min
    • CO =HRxSV
    • stroke volume is the amount of blood ejected by the heart SV= 50-100ml
  18. Cardiac Index
    • Cardiac Index is cardiac output divided by body surface area
    • CI =CO/BSA
    • BSA is determined by ht and wt
    • Normal is 2.4-4 l/min
    • CI less that 2 = shock state
  19. Septic shock
    • Characterized by bacterial endotoxins
    • endotoxins produce massive arterial vasodialation
    • severe decrease bp
    • decreased SVR less than 600 (normal 800-1200)
    • The heart compensates by increasing the HR and contractility=increased CO
    • heart beats faster and harder
  20. Cardiogenic Shock
    • Characterized by nonfunctioning ventricular wall
    • Heart loses pumping ability
    • severe decrease in BP
    • decreased CO
    • vascular system compensates by vasoconstriction
    • SVR increases above 1600
  21. Complications of the SWAN
    • Pneumothorax
    • infection
    • balloon rupture
    • pulmonary infarction
    • pulmonary artery rupture
    • ventricular tachycardia
  22. Review of Must Know numbers
    • CVP-measures rt sided fluid status 2-6
    • PA - pressure in the pulmonary artery systolic 20-30 and diastolic 8-15
    • CO -blood flow through heart in liters 4-8
    • CI- standardize measure of CO/BSA 2.4-4
    • PCWP (wedge) Left ventricular preload 4-12
    • SVR - systemic vascular resistance 800-1200

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